A patio can either be an exterior room, an extension of the house or just a concrete slab with chairs, a table and maybe a grill. It also can have many more features.
There are a few sites which offer great design ideas for patios.
MyLandscapes offers patio design ideas that require low maintenance and have roof gardens and terraces as their main esthetic feature.
LandscapeDesignByLee specializes in custom patio designs, entrance gardens, pool scape, shade gardens, cottage gardens and even walkways and driveways.
RaleighLandscape specialize in ponds, patios, lawns and others. These projects are executed by professionals with experience and a diverse background.
AbloomLandscapeContractor have an experience in the landscaping business of 30 years. They can help you with any landscaping features.